Chapter 8: Intraocular Refractive Surgery
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In its early history, refractive surgery was synonymous with corneal refractive (keratorefractive) surgery. In recent years, the scope of refractive surgery has expanded to include lensbased intraocular surgical techniques for achieving refractive outcomes.
In crystalline lens–sparing procedures, termed phakic intraocular lens implantation, the implantation of a phakic intraocular lens (PIOL) allows treatment of more extreme refractive errors, especially high myopia. Available PIOLs in the United States include iris-fixated and posterior chamber (sulcus) lenses for myopia. Outside the United States, angle-supported, iris-fixated, and posterior chamber lenses are available for hyperopia and myopia, and some phakic toric intraocular lenses (IOLs) are available to correct both myopic and hyperopic and astigmatism.
In crystalline lens–extraction procedures, termed refractive lens exchange (RLE), the patient’s lens is removed and replaced with a prosthetic lens to address refractive errors of the eye. Advances in cataract surgical technique (small, predictable wounds, precision biometry, and improved IOL power calculation formulas) and expanded choices of intraocular lenses have afforded more accurate and predictable refractive outcomes allowing the elective correction of spherical, astigmatic, and presbyopic refractive errors.
The combination of corneal and intraocular refractive surgery, termed bioptics, allows patients at the extremes of refractive error, both spherical (myopia, hyperopia) and cylindrical (astigmatism), to attain good, predictable outcomes by combining the advantages of the intraocular refractive surgery in treating large corrections with the adjustability of keratorefractive techniques. In addition, the optical quality may be improved by dividing the refractive correction between the 2 surgical procedures.
This chapter discusses the intraocular surgical techniques that are now, or are soon expected to be, available to the refractive surgeon.
Phakic Intraocular Lenses
The history of the PIOL in correcting refractive error began in Europe in the 1950s, but manufacturing-quality limitations precluded these IOLs from achieving widespread use until the 1990s. Refinements in IOL design have reduced the incidence of complications and, consequently, increased the popularity of these PIOLs both inside and outside the United States. Within the United States, 3 PIOLs are currently approved by the US Food and Drug Administration (FDA) for myopia: 2 nonfoldable polymethyl methacrylate (PMMA) iris-fixated PIOLs, and 1 foldable collamer posterior chamber PIOL. The 2 nonfoldable PMMA lenses are identical in design but have different dioptric ranges. Outside the United States, available models include foldable versions of the PIOLs, hyperopic and toric versions of all of these PIOLs, and an angle-fixated PIOL. Representative lenses in each category (Table 8-1) are discussed in the following sections.
Huang D, Schallhorn SC, Sugar A, et al. Phakic intraocular lens implantation for the correction of myopia: a report by the American Academy of Ophthalmology. Ophthalmology. 2009;116(11):2244–2258.
Excerpted from BCSC 2020-2021 series: Section 13 - Refractive Surgery. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.